An inker for a lithographic printing press includes an ink fountain having a rotatable fountain roller for picking up the ink from the fountain. The ink is transferred from the fountain roller by a plurality of ink distribution rollers, which in turn transmit the ink to a plurality of form rollers for applying the ink to the plate cylinder. The ink distribution rollers include vibrating rollers, which are in contact with respective ones of the ink form rollers and which oscillate axially as they rotate. Similarly, water is applied to areas of the plate cylinder where no image is desired to prevent the deposition of ink on those areas. Lithographic printing presses typically use a series of dampening rollers to pick up water from a pan or sump and transfer it to the plate cylinder.
"Ghosting" is a common problem encountered in such lithographic printing presses having an inker as described above. The ghosting problem results from ink starvation on certain areas of the plate cylinder. For example, when it is desired to print images in the same color and shade where the image is printed by at least two portions on the plate cylinder, one portion of which extends angularly relative to the other portion, one portion of the image will not be the same shade as the other portion. Thus, a distinct change in color occurs in the image, which is noticeable to the human eye. Typically, the portion of the image which is printed by the ink-receptive plate area of the greatest circumferential extent around the plate cylinder (the circumferential section of the plate cylinder having the greatest percentage of ink-receptive area) is lighter in shade than the other portion of the image and the change in shade occurs along a line.
Another problem commonly encountered in lithographic printing presses is the problem of "railroad tracking". This problem occurs when a dampening form roller picks up ink from the plate cylinder. during the rotation of the dampening form roller with respect to the plate cylinder, ink may be deposited on certain non-ink-receptive areas of the plate cylinder, thereby causing streaks of ink to be deposited on the plate cylinder, which results in such streaks appearing in unwanted areas on the final print product. Water streaks may also appear on the plate cylinder, which necessitates the use of alcohol and alcohol substitutes in the dampening fluid to break up the surface tension of the water and eliminate streaking.